1. Field of the Invention
The present invention relates to a disk cassette loading mechanism for employment in a disk driving apparatus, such as a magnetic disk apparatus, which receives a disk cassette holding an information recording disk (hereinafter referred to simply as "disk") therein for recording information in the disk or reproducing information stored in the disk.
2. Description of the Prior Art
It has been a general practice to push a disk cassette by hand into a disk driving apparatus to place the disk cassette on a cassette holder retained at a cassette unloading position by a locking mechanism in loading the disk on a disk driving apparatus. In such a conventional disk driving apparatus of a manual loading system, the locking mechanism retaining the cassette holder at the disk unloading position apart from a rotative driving mechanism is disengaged upon the arrival of the disk cassette at a predetermined position on the cassette holder to allow the cassette holder to be moved to a cassette loading position, then the disk held in the disk cassette is loaded on the rotative driving mechanism and, at the same time, a recording/reproducing head (hereinafter referred to as "magnetic head") is brought into contact with the surface of the disk to record information in the disk or to reproduce information stored in the disk. In unloading the disk cassette from the conventional disk driving apparatus, it sometimes occurs that the disk cassette is ejected before the cassette holder is shifted exactly from the disk loading position to the disk unloading position after the magnetic head has been separated from the disk. In such a case, it is possible that the magnetic head remains at the operative position after the disk has been removed from the disk driving mechanism and strikes accidentally against the adjacent parts to break itself entailing damages in the internal mechanisms.
To obviate such troubles, various disk driving apparatus of an automatic loading system have been proposed. Japanese Utility Model Provisional Publication No. 61-149162 of the applicant of this patent application discloses such a disk driving apparatus of an automatic loading system.
As shown in FIG. 7, this known disk driving apparatus has an automatic loading/ejecting mechanism comprising, as principal components, a swing lever 51 pivotally supported on a shaft 50, a slider 53 capable of reciprocating along a guide shaft 52, and a torsion coil spring 54 having one end, i.e., a lower end as viewed in FIG. 7, connected to the free end of the swing lever 51 and the other end, i.e., an upper end as viewed in FIG. 7, connected to the slider 53. When the swing lever 51 is turned on the shaft 50, the slider 53 is caused to slide along the guide shaft 52 by the torsion coil spring 54. As shown in FIG. 8, the slider 53 has an arm 59 provided with a pin 58 which engages a recess 57 formed in a disk cassette 56 in the lower surface thereof facing a disk driving mechanism. When the disk cassette 56 is inserted in the disk driving apparatus to a predetermined position, the pin 58 of the arm 59 engages the recess 57 of the disk cassette from below as viewed in FIG. 9. After the pin 58 has engaged the recess 57 of the disk cassette, the slider 53 is allowed to slide in a predetermined direction for loading the disk cassette 56.
This disk driving apparatus uses the relation between the resilience and displacement of the torsion coil spring 54 for loading the disk cassette 56. In loading the disk driving apparatus with the disk cassette 56, the torsion coil spring 54 is positioned at a standby position as indicated by solid lines in FIG. 10 and the swing lever 51 is restrained from turning by an ejecting lever 60. When the slider 53 is pressed backward, namely, in the direction of an arrow X (FIGS. 7, 9, 10) by the disk cassette 56, the torsion coil spring 54 caused to turn counterclockwise about a hole 61 formed in the swing lever 51 to receive the lower end of the torsion coil spring 54. As the torsion coil spring 54 is turned in that manner, the distance between the upper and lower ends thereof decreases gradually. The distance is reduced to the smallest value upon the arrival of the torsion coil spring 54 at a position indicated by dotted lines in FIG. 10, where both the upper and lower ends of the torsion coil spring 54 are on a straight line P perpendicular to the direction of the arrow X and the resilience of the torsion coil spring 54 is increased to the maximum. The disk cassette 56 is pushed into the disk driving apparatus by hand or by mechanical means until the torsion coil spring 54 is turned to the position indicated by dotted lines in FIG. 10. Referring to FIGS. 9 and 10, while the slider 53 is moved in the direction of the arrow X turning the torsion coil spring 54 toward the position indicated by dotted lines, the extremity 62 of the arm 59 slides along the inclined surface 64 extending obliquely upward to the right, as viewed in FIG. 9, of the control plate 63 of a cassette holder 67 and, finally, the pin 58 of the arm 59 projects into a disk inserting path 65 to engage the recess 57 of the disk cassette 56, so that the slider 53 and the disk cassette 56 are combined.
As the slider 53 is moved further in the direction of the arrow X further turning the torsion coil spring 54 in a counterclockwise direction, the upper end of the torsion coil spring 54 engaging a hole 66 formed in the slider 53 is moved beyond the straight line P. Upon the passage of the upper end of the torsion coil spring 54 across the straight line P, the torsion coil spring 54 is caused to recoil by the energy stored therein, and hence the upper end of the torsion coil spring 54 moves automatically further in the direction of the arrow X as indicated by alternate long and two short dashes lines in FIG. 10, whereby the disk cassette 56 is pulled automatically into the disk driving apparatus. Slightly before the torsion coil spring 54 arrives at the final position indicated by alternate long and two short dashes lines in FIG. 10, the disk cassette 56 arrives at a position directly above a disk driving mechanism and, at the same time, an unlocking lug 68 fixedly provided at the rear end of the slider 53 strikes against a locking lever, not shown, to disengage a locking mechanism, so that the disk cassette is mounted on the disk driving mechanism.
This disk driving apparatus, however, has drawbacks. That is, since the arm 59 swings below the disk cassette 56 in a vertical plane to bring the pin 58 into engagement with and to disengage the same from the recess 57 of the disk cassette 56, it is difficult to form the disk driving apparatus in a comparatively small height. When the arm 59 is arranged so as to swing laterally in a horizontal plane, the width of the disk driving apparatus will be increased.